* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: "Poppins", sans-serif;
}

body {
  background: radial-gradient(circle at top left, #667eea, #764ba2, #6b8dd6);
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.container {
  width: 90%;
  max-width: 650px;
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  padding: 40px;
  border-radius: 25px;
  text-align: center;
  box-shadow: 0 0 30px rgba(0, 0, 0, 0.2);
  transition: transform 0.3s ease;
}
.container:hover {
  transform: scale(1.02);
}

h1 {
  margin-bottom: 15px;
  font-size: 2rem;
}
h2 {
  font-size: 1.5rem;
  margin: 20px 0 10px;
}
p {
  color: #ddd;
  margin-bottom: 15px;
}

input {
  width: 90%;
  padding: 10px;
  margin: 10px 0;
  border: none;
  border-radius: 10px;
  font-size: 1rem;
  outline: none;
}
input:focus {
  border: 2px solid #4caf50;
}

.btn {
  padding: 12px 25px;
  background: linear-gradient(90deg, #4caf50, #81c784);
  border: none;
  border-radius: 10px;
  color: white;
  font-size: 1rem;
  cursor: pointer;
  transition: all 0.3s ease;
}
.btn:hover {
  transform: scale(1.05);
  background: linear-gradient(90deg, #43a047, #66bb6a);
}

.option {
  background: #fff;
  color: #333;
  margin: 10px 0;
  padding: 12px;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.3s;
}
.option:hover {
  background: linear-gradient(90deg, #43a047, #66bb6a);
  color: #fff;
}

.hidden {
  display: none;
}

.quiz-header {
  display: flex;
  justify-content: space-between;
  font-weight: 600;
  margin-bottom: 15px;
}

.timer-container {
  margin-top: 15px;
}
.timer {
  font-size: 1.1rem;
  font-weight: bold;
}
.progress-bar {
  width: 100%;
  height: 10px;
  background: rgba(255, 255, 255, 0.3);
  border-radius: 10px;
  overflow: hidden;
  margin-top: 5px;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, #4caf50, #81c784);
  width: 100%;
  transition: width 1s linear;
}

#review {
  text-align: left;
  margin-top: 20px;
  background: rgba(255, 255, 255, 0.15);
  padding: 15px;
  border-radius: 15px;
  max-height: 300px;
  overflow-y: auto;
}
.review-item {
  margin-bottom: 12px;
  padding: 10px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}
.review-item:last-child {
  border-bottom: none;
}
.review-item h4 {
  font-size: 1rem;
  color: #fff;
}
.review-item p {
  margin-top: 4px;
  font-size: 0.95rem;
}
.correct {
  color: #4caf50;
  font-weight: 600;
}
.wrong {
  color: #ff5252;
  font-weight: 600;
}
.correct-answer {
  color: #ffd700;
  font-style: italic;
}

@media (max-width: 600px) {
  h1 { font-size: 1.5rem; }
  h2 { font-size: 1.2rem; }
  .btn { font-size: 0.9rem; }
}